What is the proper way to BBT temp?

I feel like my temps is not accurate! what is the proper way to BBT temp? When do you discord a temp? what affect your temps? I just feel like I’m doing something wrong. I normally go to sleep from 2 AM to 6:40 am. On the weekends I sometimes drink. I move in my sleep. Sometimes I wake up earlier than 6:40. When should I start taking ovulation test?